Shaped charges come in many sizes and shapes and are used mainly for military weaponry and oil well perforating; to a lesser extent demolition and rescue are also users of this complex technology.
The term shaped charge literally refers to a quantity of explosive that is shaped in some way to focus its energy. Shaped charge is also more loosely used to mean a shaped quantity of high explosive with a metal or other liner, a containment body and a means of detonation.
The concept of shaping an explosive charge, in order to focus its energy was known in 1792. (“The History of Shaped Charges” Donald R Kennedy)
In the 1930's Misznay and Chardin, Hungarian and German physicists, created a shaped explosive device that forms a shuttlecock like projectile that can be tailored to very long standoff. This type of device is commonly known as a Misznay Chardin device, a Self Forging Frag or an Explosively formed Projectile (EFP). They discovered that when a disc of explosive with a concavity on one side is detonated correctly it will focus its energy perpendicular to the plane of the disc in both directions, and if the cavity in the explosive disc was lined with a ductile metal it would be formed into a high speed projectile. This dished liner for this device resembled a shallow dished platter much like a tea saucer. Because of the shallowness of the concavity of the liner and the flatness of the detonation wave attacking it, ninety percent of the liner mass is folded into an EFP, unlike a Munroe effect shaped charge whose jet is only approximately 20% of the liner mass.
Although EFP devices qualify as shaped charges in the common vernacular, they operate on a different principle than a Munroe shaped charge. EFP devices have lower projectile velocities, greater projectile mass, penetrate less deep but make larger holes than a Munroe effect shaped charge yet not super caliber holes.
Conventional EFP producing charges have been used in antitank and other directed energy weapons for many years and have been refined in an effort to make a high speed primary jet for missile seeker removal, but will not produce a hole in an infinite target large enough to place another device of the same size at the bottom of that hole.
Throughout the history of shaped charges the primary effort of research in this field was directed toward depth of penetration by the jet. Although hole size is worth considering, little research has been done on significantly increasing jet diameter and cross-sectional shape of the jet to produce a larger hole diameter. In oil field applications a larger hole is most desirable as the flow area of the hole increases rapidly with an increase in hole diameter. With the ability to produce a full caliber hole, a follow on or follow through device can be deployed into the hole to the correct standoff from the bottom of the hole. When detonated at the correct standoff this will increase the hole depth by that of the primary hole producing device, this can be repeated numerous times in the same hole.